Corey-Bakshi-Shibata Reduction
Itsuno-Corey Reduction

The
enantioselective reduction of ketones using borane
and a chiral oxazaborolidine as catalyst (CBS catalyst). Usually, MeCBS
is used (R'' = Me, but selectivity may be increased by varying this substituent).

Mechanism of the Corey-Bakshi-Shibata Reduction

The mechanism depicted (E. J. Corey, C. J. Helal, Angew. Chem. Int.
Ed., 1998, 37, 1986-2012.
DOI) portrays the rationale for the enantioselectivity and
high reaction rates, which are influenced only by the CBS catalyst. This
catalyst is a combination of both a Lewis acid and a chiral auxiliary!